Seismology is the study of earthquakes, which occur when stress causes rocks under the Earth's crust to elastically deform until they break, rebounding and snapping back into their original shape. This elastic rebound releases energy in the form of seismic waves, causing the shaking that defines an earthquake. Faults form from tectonic stresses and are breaks in the Earth's crust. The focus is the point within the earth where an earthquake originates, while the epicenter is the point on the surface directly above the focus.

1. EARTHQUAKES

3. IMPORTANT TERMS
• Seismology:
– The study of
earthquakes…seismo
means “shake”
• Fault:
– A break in the Earth’s
crust
– formed from stress
from tectonic forces

4. • Stress:
– Any push or pull on the Earth’s crust
– Causes deformation
Plastic Deformation
•Rocks bend like
molded clay
•Does NOT cause
earthquakes

5. • Deformation:
– The change in the shape of rock in response to
stress
Elastic Deformation
•Rock bends until it breaks
•Elastic rebound
•Rock snaps back into
original shape
•This causes earthquakes

6. The point on the
Earth’s
surface…directly
above the focus
Point inside the
earth where an
earthquake
begins